Edge rails 3.1beta

Hi all,

I just decided to switch to edge rails. So, I added the following
gem ‘rails’, :git => ‘git://github.com/rails/rails.git’
gem “rack”, :git => “git://github.com/rack/rack.git”

to my Gemfile.

As soon as I tried to run my app, one of my controllers throw this
error:

ActionView::Template::Error (undefined method `[]’ for #<MyApp:
0x00000102c26a20>):

inside the view for MyApp controller, I have code that renders a
select HTML form element. eg,

f.select(:stuff, MyApp::STUFFS)

where STUFFS is an options array defined in the MyApp.rb (model)

Does anyone know why?
My application works fine under Rails 3.0.3

thanks,

Grace